Accumulator for conveyor system

ABSTRACT

An accumulator for storing rows of articles thereon includes a frame having upper and lower shafts rotatably supported thereon. A plurality of sprockets are mounted on each of the upper and lower shafts for rotation therewith. Each of the sprockets defines a radius. An electric motor is provided for selectively rotating the shafts and the sprockets mounted thereon. A plurality of roller chains are mounted on associated pairs of the upper and lower sprockets for movement when the shafts and sprockets are rotated. Each of the roller chains includes a plurality of spaced apart pins. A plurality of link are carried on each of the roller chains for movement therewith. Each of the links has a pair of apertures formed therethrough and a pair of arcuate slots formed therethrough. The apertures and the slots having respective first edges which define a straight line and respective second edges which define a radius. The radius defined by each of the links is substantially equal to the radius defined by each of the sprockets. Lift rails and lift finger subassemblies are secured to each of the links which define shelf positions for supporting rows of articles thereon. The lift finger subassemblies are oriented at a small angle relative to the links to retain the articles on each of the shelf positions.

This is a continuation of copending application(s) Ser. No. 08/006,614filed on Jan. 21, 1993, now U.S. Pat. No. 5,255,773.

BACKGROUND OF THE INVENTION

This invention relates in general to accumulators for conveyor systemsand in particular to an improved structure for an accumulator havingvertically movable shelves.

Conveyors are well known devices which are commonly used in productionline situations to transport articles from one location to another. Forexample, a conveyor may be used to transport cartons of a product froman upstream filling station, wherein the cartons are filled with theproduct and sealed, to a downstream packaging station, wherein thesealed cartons are packaged into larger shipping containers. Manyconveyor system structures are known in the art for accomplishing thisbasic function.

Usually, the conveyor system is designed to provide a continuous flow ofarticles from the upstream station on the production line to thedownstream station. However, occasionally, it becomes necessary to haltthis continuous flow of articles. For example, the flow of articles mayneed to be stopped because one or more of the articles becomes jammed inthe production line and must be cleared. Alternatively, the flow ofarticles may need to be halted because the downstream processingequipment is temporarily unable to accept the continued flow ofarticles. To accommodate this, some known conveyor systems are providedwith a control system which simply ceases the flow of articlestherethrough when this occurs. This is frequently undesirable, though,because it requires that the upstream equipment on the production linecease operation until the problem located downstream is corrected.

To address this problem, it is known to provide one or more accumulatorsmidstream within a conveyor system. An accumulator is a device which istypically located between first and second individual conveyors in aconveyor system. When the production line is operating normally, theaccumulator receives products from the first conveyor and merelytransports them therethrough to the second conveyor. However, when aproblem occurs in the downstream portion of the production line, such asdescribed above, the accumulator receives products from the firstconveyor and temporarily stores them therein until the problem iscorrected. Thus, the accumulator functions to temporarily prevent theflow of the articles downstream thereof, while permitting the upstreamportion of the production line to continue, at least temporarily, innormal operation.

Many different accumulator structures are known in the art. One type ofaccumulator structure is known as a horizontal accumulator. A typicalhorizontal accumulator includes a plurality of horizontally spaced,parallel storage paths. One or more entrance gates are provided fordirecting the flow of products from the first conveyor to one of thestorage paths as necessary. In this manner, the flow of productsdownstream is temporarily prevented. When it is desired to resume theflow of products downstream of the horizontal accumulator, one or moreexit gates are opened so as to direct the stored products from thestorage paths into the second conveyor. While horizontal accumulators ofthis general type are effective for temporarily preventing the flow ofproducts therethrough, they have been found to be inefficient because oftheir physical size. Specifically, the parallel storage paths of thesehorizontal accumulators occupy an undesirable large amount of floorspace in the facility in which they are used.

To minimize this floor space problem, a second type of accumulatorstructure, known as a vertical accumulator, has been developed. Atypical vertical accumulator includes a plurality of vertically spaced,parallel storage paths. Articles passing through the verticalaccumulator are received from the first conveyor and stored in groups onshelves. When a first shelf is filled with a plurality of articles, itis elevated above the vertical height of the first and second conveyorsto permit a second shelf to be filled in a similar manner. When it isdesired to return the stored products to the conveyor system, theshelves are sequentially lowered to permit the articles to be fed to thesecond conveyor. Thus, it can be seen that vertical accumulators occupya relatively small amount of floor space in the facility in which theyare used and, therefore, are generally preferable to the horizontalaccumulators described above.

Many different vertical accumulator structures are known in the art. Ina first type of vertical accumulator, the articles are lifted above thevertical height of the conveyor system by opposed lifting flanges whichengage the peripheral edges of the articles. This type of verticalaccumulator is undesirable because the spacing between the liftingflanges must be varied when articles of varying size are to be stored.In a second type of vertical accumulator, the articles are lifted abovethe vertical height of the conveyor system by shelves formed from aplurality of individual fingers. The fingers pass upwardly betweencantilevered rollers of the conveyor to lift the articles upwardly. Thecapacity of both of these types of vertical accumulators is limited bythe vertical space available above the conveyor.

A third type of vertical accumulator uses an endless member mountedabout a conveyor section. A plurality of cantilevered shelves areattached at spaced intervals to the endless member, while a shroud isdisposed about the endless member and shelves above the conveyorsection. When accumulation of the articles is desired, the endlessmember is rotated, causing the cantilevered shelves to sweep a row ofthe articles laterally off of the conveyor section and upwardly againstthe surrounding shroud. The shroud functions to retain the articles onthe shelves as they are swept in an arcuate path off of the conveyorsection and upwardly. As the endless member is further rotated,additional shelves can be stored with products. Because the shroudextends over the upper portion of the vertical accumulator, the shelvesof stored products may be swept in an arcuate manner over such upperportion and downwardly on the other side of the vertical accumulator. Asa result, this type of vertical accumulator has a relatively largestorage capacity. However, it has been found that this type of verticalaccumulator is not easily adaptable for use with articles of varyingsize because such articles must engage the enclosing shroud to functionas described above. As a result, the shroud must be re-positioned eachtime articles of a different size are to be accumulated. This can be adifficult and time consuming operation. Thus, it would be desirable toprovide an improved structure for an accumulator which can easilyaccommodate articles of varying size.

SUMMARY OF THE INVENTION

This invention relates to an improved structure for an accumulator whichhas a relatively high storage capacity, occupies a relatively smallamount of floor space, and is readily adapted for use with products ofvarying size. The accumulator includes storage shelves positionedadjacent the conveyor. Each storage shelf includes a lift rail, a firstrow of fingers cantilevered from the lift rail, and may include a secondrow of fingers cantilevered from the same lift rail. The lift rail ismounted to an endless chain loop which meshes with an upper and a lowersprocket. When articles are not being accumulated, the lift rail isposition with the first row of fingers positioned between the rollers ofthe conveyor. The fingers are positioned below the tops of the rollers,and so do not interfere with the movement of articles along theconveyor. The second row of fingers is located above the path ofarticles being conveyed. The articles are transported on the conveyorbetween the first and second rows of fingers. In order to accumulate thearticles, the first row of fingers is moved upwardly between theconveyor rollers to lift a first group of articles off of the conveyor.As subsequent groups of articles are accumulated upon the shelves, thelift rails are incrementally advanced upwardly by the endless chain. Asthe chain passes over the upper sprocket to the rear of the accumulator,the shelves and articles are inverted. On the rear of the accumulator,the articles are supported by the second row of fingers. The movement ofthe endless chain may be reversed to deposit the articles back upon theconveyor. No shroud is required to retain the articles on the shelves,since the articles are supported by the fingers or lift rail at alltimes.

Various objects and advantages of this invention will become apparent tothose skilled in the art from the following detailed description of thepreferred embodiment, when read in light of the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified schematic top plan view of an article handlingsystem including an improved accumulator in accordance with thisinvention.

FIG. 2 is a perspective view of the accumulator illustrated in FIG. 1taken from the discharge end thereof;

FIG. 3 is an end elevational view of the accumulator illustrated in FIG.2 taken from the intake end thereof and schematically showing theendless chain and link subassembly.

FIG. 4 is an enlarged end elevational view of a portion of the endlesschain and link subassembly of the accumulator shown in FIG. 3, thefingers of the subassembly having been removed for clarity.

FIG. 5 is an exploded view of the portion of the chain and linksubassembly taken along line 5--5 of FIG. 4.

FIG. 6 is an enlarged elevational view of one of the inner linksillustrated in FIGS. 4 and 5, wherein an end portion thereof is shown ina preliminary flat condition.

FIG. 7 is an elevational view similar to FIG. 6 showing the inner linkafter the end portion thereof has been bent and illustrating the mannerin which the fingers are secured thereto.

FIG. 8 is a top plan view of a portion of the conveyor mechanism for theaccumulator shown in FIG. 3.

FIG. 9 is a side elevational view of the portion of the conveyormechanism illustrated in FIG. 8.

FIG. 10 is a schematic diagram illustrating an automated control systemfor the accumulator of FIG. 2.

FIG. 11 is an enlarged end elevational view of the upper portion of theaccumulator illustrated in FIG. 3.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawings, there is illustrated in FIG. 1 asimplified schematic top plan view of an article handling system,indicated generally at 10. The article handing system 10 includes anupstream processing station 11, a conveyor system 12, and a downstreamprocessing station 13. The upstream processing station 11 may, forexample, be a conventional filling station 11 which is adapted toreceive articles, such as empty cartons (not shown in FIG. 1), and fillthem with a product. The filled cartons are fed from the filling station11 through the conveyor system 12 to the downstream processing station13. The downstream processing station 13 may, for example, be aconventional packaging station 13, wherein the sealed cartons from theconveyor system 12 are packaged into larger shipping containers.

The conveyor system 12 itself is composed of a conventional firstconveyor 14 which receives the filled cartons from the filling station11. The first conveyor 14 transports the articles (in a directionindicated by the upper arrow in FIG. 1) to an accumulator, indicatedgenerally at 15, which is the subject matter of this invention. Thestructure and operation of the accumulator 15 will be explained andillustrated below in detail. The filled cartons pass from theaccumulator 15 to a conventional second conveyor 16. The second conveyor16 receives the cartons from the accumulator 15 and transports them (ina direction indicated by the lower arrow in FIG. 1) to the packagingstation 13. The upstream processing station 11, the first conveyor 14,the second conveyor 16, and the downstream conveyor 13 are conventionalin the art and form no part of this invention.

Referring now to FIG. 2, the exterior structure of the accumulator 15 isillustrated. The accumulator 15 includes an intake or upstream end whichis disposed adjacent to the first conveyor 14. Thus, as discussed above,cartons 17 are delivered from the first conveyor 14 to the intake end ofthe accumulator 15. As will be discussed in detail below, theaccumulator 15 includes a plurality of shelf positions, each of which isadapted to store a plurality of cartons 17 thereon to prevent them fromflowing through the accumulator 15 to the second conveyor 16. Thedischarge end of the accumulator 15 is adapted to discharge cartons ontothe second conveyor 16.

Referring now to FIG. 3, the structure of the accumulator 15 isillustrated in more detail from the intake end thereof. As showntherein, the accumulator 15 includes a frame 20 for rotatably supportingan upper shaft 21 which extends axially throughout the length thereof. Aplurality of upper sprockets 22 (only one is illustrated) are mounted onthe upper shaft 21 for rotation therewith. The upper sprockets 22 areaxially spaced apart from one another along the length of the uppershaft 21. Similarly, the frame 20 also rotatably supports a lower shaft23 having a plurality of lower sprockets 24 (only one is illustrated)mounted thereon. The number and spacing of the sprockets 22 and 24 canvary with the overall size of the accumulator 15. A motor 25 (see FIG.2) is mounted on the frame 20 for selectively rotating the upper shaft21, as will be explained in detail below.

The accumulator 15 further includes a plurality of endless chain andlink subassemblies, indicated generally at 30 (only one is illustrated).Each of the endless chain and link subassemblies 30 respectively extendsabout one of the associated pairs of the upper sprockets 22 and thelower sprockets 24. Thus, each of the endless chain and linksubassemblies 30 meshes with one of the upper sprockets 22 and one ofthe lower sprockets 24. As a result, when the upper shaft 21 (and theupper sprockets 22 mounted thereon) are rotated by the motor 25, theendless chain and link subassemblies 30 (and the lower shaft 23 havingthe lower sprockets 24 mounted thereon) are all rotated therewith.

The structure of one of the endless chain and link subassemblies 30 isillustrated in more detail in FIGS. 4 and 5. As shown therein, thesubassembly 30 includes an endless chain member, indicated generally at31, which is preferably embodied as a conventional roller chain. Theroller chain 31 includes a plurality of rollers 32, each of which isrotatably mounted on an elongated pin 33. A plurality of connectingmembers 34 are press fit onto adjacent pins 33 for joining them (and therollers 32 rotatably supported thereon) together to form the rollerchain 31. The structure of the roller chain 31 thus far described isconventional in the art.

The endless chain and link subassembly 30 further includes a pluralityof inner links 35 and outer links 36, all of which are secured to theroller chain 31 for movement therewith. FIG. 6 illustrates a flat blank35a of metallic material from which one of the inner links 35 can bemanufactured. As shown therein, the blank 35a is generally rectangularin shape, but is provided with a pair of opposed ear portions whichextend generally apart from one another. First and second pairs ofapertures 35b and 35c are formed through the blank 35a. Also, a pair ofarcuate slots 35d are formed through the ear portions of the blank 35a.The blanks 35a, as well as the apertures 35b and 35c and the arcuateslots 35d, may be formed by any conventional metal forming process, suchas stamping. Then, a portion of the blank 35a is bent along the dottedline 35e so as to extend perpendicular to the remainder thereof to formthe inner link 35, as shown in FIG. 7.

The outer edges (the right edges when viewing FIG. 6) of the first pairof apertures 35b and the outer edges of the arcuate slots 35d arelinearly and vertically aligned, as shown by the dotted line 35f. Theinner edges (the left edges when viewing FIG. 6) of the first pair ofapertures 35b and the inner edges of the arcuate slots 35d are alignedalong an arc defined by a radius R, as shown by the dotted line 35g. Allof the inner links 35 and all of the outer links 36 are formed in thismanner. The purpose for this structure will be explained below.

Referring back to FIGS. 4 and 5, it can be seen that each of the innerlinks 35 is mounted on four adjacent pins 33 of the roller chain 31.Thus, when one of the inner links 35 is installed on the roller chain31, the elongated pins 33 are received through the first pair ofapertures 35b, and through the slots 35d. As also shown in FIG. 5,adjacent ones of the inner links 35 are spaced apart from one another bytwo elongated pins 33. Between adjacent ones of the inner links 35, aspacer bracket 37 is provided. Each of the spacer brackets 37 is formedfrom a flat strap having a pair of apertures 37a formed therethrough.The spacer brackets 37 are installed on the roller chain 31 such thatthe two elongated pins 33 located between adjacent ones of the innerlinks 35 are received in the apertures 37a. Thus, each of the spacerbrackets 37 receives two adjacent pins 33 through its apertures 37a. Theapertures 35b formed through the inner link 35 and the apertures 37aformed through the spacer brackets 37 are sized to be slightly largerthan the diameters of the elongated pins 33 received therein. Thus, theinner links 35 and the spacer brackets 37 are only loosely mounted onsuch pins 33 so as not to inhibit the free movement thereof.

As shown in FIG. 6, the outer links 36 are shaped generally the same asthe inner links 35 and are formed from a similar blank of material 36a(not shown) having first and second pairs of apertures 36b and 36c andarcuate slots 36d. For a reason which will become apparent below,however, the location of the second pair of apertures 36c in the outerlinks 36 is slightly offset from the location of the second pair ofapertures 35c in the inner links 35. The outer links 36 are mounted onthe roller chain 31 in an alternating overlapping manner relative to theinner links 35. Thus, as shown in FIGS. 4 and 5, the upper slot 36dformed on one of the outer links 36 is mounted on the same elongated pin33 of the roller chain 31 as the lower slot 35d formed on the adjacentone of the inner links 35. Similarly, the lower slot 36d formed on oneof the outer links 36 is mounted on the same elongated pin 33 of theroller chain 31 as the upper slot 35d formed on adjacent one of theinner links 35.

Means are provided for retaining the inner links 35 and the outer links36 on the elongated pins 33 of the roller chain 31 during use. In theillustrated embodiment, this means for retaining includes a plurality ofretainer brackets 38. Each of the retainer brackets 38 is formed from aflat strap having a pair of apertures 38a formed therethrough. Theretainer brackets 38 are installed on the roller chain 31 such that thetwo adjacent elongated pins 33 are received in the apertures 38a. Unlikethe inner link apertures 35b, the outer link apertures 36b, and thespacer bracket apertures 37a, the retainer bracket apertures 38a aresized to be slightly smaller than the diameters of the elongated pins 33received therein. Thus, the retainer brackets 38 are press fit onto suchpins 33, thereby retaining the inner links 35, the outer links 36, andthe spacer brackets 37 thereon to form the endless chain and linksubassembly 30.

As mentioned above, the outer links 36 are mounted upon the roller chain31 in an alternating overlapping manner relative to the inner links 35.Thus, when the endless chain and link subassembly 30 is assembled asdescribed above, all of the outer links 36 are offset from the innerlinks 35 (and from the roller chain 31 itself) by a distance which isequal to the thickness of the opposed ear portions of the inner links 35(i.e., the thickness of the blank 35a illustrated in FIG. 4). Tocompensate for this, the locations of the second pair of apertures 36cformed through the outer links 36 are offset from the locations of thesecond pairs of apertures 35c formed through the outer links 35. Theamount of this offset is equal to the thickness of the opposed earportions of the inner links 35. Thus, as best shown in FIG. 6, theapertures 36c formed through the outer links 36 are located slightlycloser to the right edge of the bent portion thereof than the apertures35c formed through the outer links 35c. As a result of this offsettingcompensation arrangement, it will be appreciated that all of theapertures 35c and 36c are linearly aligned (upwardly and downwardly whenviewing FIG. 3) when the endless chain and link subassembly 30 isassembled. The purpose for maintaining these apertures 35c and 36c insuch linear alignment will be explained below.

As best shown in FIG. 3, a plurality of shelf positions are definedthroughout the length of the endless chain and link subassembly 30. Inthe illustrated embodiment, thirty- three of such shelf positions areprovided on the endless chain and link subassembly 30, although agreater or lesser number may be provided if desired. Most of the shelfpositions are adapted to store respective pluralities of cartons 17thereon, in a manner which will be described in detail below. However,as will also be explained below, a small number of the shelf positionscannot store any cartons 17 thereon. A first group of shelf positions(the first through fifteenth) are identified in FIG. 3 as A1 throughA15. A second group of shelf positions (the sixteenth throughtwenty-eighth) are identified in FIG. 3 as B16 through B28. A thirdgroup of shelf positions (the twenty-ninth only) is identified in FIG. 3as C29. A fourth group of shelf positions (the thirtieth throughthirty-third) are identified in FIG. 3 as D30 through D33.

Referring now to FIG. 7, the structure of one of the shelf positions Allis illustrate in detail. As shown therein, a lift rail 40 is secured tothe inner link 35. The lift rail 40 has an inverted-C cross sectionalshape, including a central portion which is secured to the inner link 35by means of a pair of threaded fasteners 41 and having upper and lowerend flanges. The threaded fasteners 41 extend through apertures 42 whichare formed through the central portion of the lift rail 40 and which arealigned with the second pair of apertures 35b formed through the bentportion of the inner link 35. In the illustrated embodiment, the secondpair of apertures 35b formed through the bent portion of the inner link35 are provided with respective threaded extruded portions into whichthe threaded fasteners 41 are received. However, the lift rail 40 may besecured to the inner link 35 by any conventional means.

As shown in FIG. 8, the lift rail 40 is an elongated member whichextends longitudinally throughout the accumulator 15. As mentionedabove, a plurality of endless chain and link subassemblies 30 are spacedlongitudinally throughout the accumulator 15. The lift rail 40 issecured to each of the endless chain and link subassemblies 30 in themanner described above. Thus, when the endless chain and linksubassemblies 30 are moved by the motor 25 as described above, the liftrail 40 is raised and lowered therewith. A similar lift rail 40 issecured to each of the other inner and outer links 35 and 36 whichconstitute the remainder of the first group of shelf positions A1through A15, to each of the inner and outer links 35 and 36 whichconstitute the second group of shelf positions B16 through B28, and toeach of the inner and outer links 35 and 36 which constitute the thirdgroup of shelf positions C29. However, for a reason which will beexplained below, no lift rails 40 are provided to the portions of theendless chain and link subassembly 30 which constitute the fourth groupof shelf positions D30 through D33.

Again referring to FIG. 7, it can be seen that a lift finger subassembly45 is secured to each of the upper and lower end flanges of the liftrail 40. The lift finger subassemblies 45 are secured to the upper andlower end flanges of the lift rail 40 by threaded fasteners 46 whichextend through aligned apertures formed therein. In the illustratedembodiment, the apertures formed through the upper and lower end flangesof the lift rail 40 are provided with respective threaded extrudedportions into which the threaded fasteners 46 are received. However, thelift finger subassemblies 45 may be secured to the lift rail 40 by anyconventional means.

As most clearly seen in FIG. 8, each of the lift finger subassemblies 45is formed generally in the shape of a comb, including a central baseportion 45a having a plurality of individual lift fingers 45b extendingoutwardly therefrom. The base portions 45a of the lift fingersubassemblies 45 are secured to the lift rail 40 by the threadedfasteners 46, as described above. Each of the shelf positions A1 throughB28 of the accumulator 15 is defined by a plurality of lift fingersubassemblies 45 which are fastened in adjacent relationship with oneanother along the length of the associated lift rail 40.

The lift finger subassemblies 45 are preferably formed as a unitarypiece to facilitate proper alignment thereof during installation. It hasbeen found desirable to mold the lift finger subassemblies 45 from arelatively rigid, light weight plastic material. Each of the individuallift fingers 45b has a cross-sectional shape which is elongated in thedirection perpendicular to the plane defined by the base portion 45a.The elongated cross-section provides the lift fingers 45b with adequatestiffness to support cartons 17 thereon, while minimizing the weight ofthe lift fingers 45b.

The individual lift fingers 45b of the lift finger subassemblies 45extend outwardly from the lift rail 40 to define the shelf A11.Preferably, these individual lift fingers 45b extend at an anglerelative to a horizontal plane extending perpendicular relative to thevertical plane defined by the central portion of the lift rail 40. Asshown in FIG. 7, the angle X represents the angle at which each of theindividual lift fingers 45b extend relative to such perpendicularhorizontal plane. It has been found desirable to define the angle X tobe approximately from two to four degrees.

A similar plurality of lift finger subassemblies 45 (having individuallift fingers 45b provided thereon) is secured to each of the upper andlower end flanges of the other lift rails 40 which constitute theremainder of the first group of shelf positions A1 through A15. As shownin FIG. 3, however, only a single plurality of lift finger subassemblies45 is secured to one of the end flanges of each of the lift rails 40which constitute the second group of shelf positions B16 through B28.Thus, individual lift fingers 45b are provided on only the lower endflanges of the lift rails 40 in the second group of shelf positions B16through B28. No lift finger subassemblies 45 are secured to the liftrails 40 which constitute the third group of shelf positions C29. Asmentioned above, there are no lift rails 40 provided for any of thefourth group of shelf positions D30 through D33. Thus, no lift fingersubassemblies 45 are provided for those shelf positions D30 through D33either. The reason for this varying number of lift finger subassemblies45 in the different groups of shelf positions will be explained below.

As mentioned above, the inner links 35 and the outer links 36 differ instructure in that their respective second pairs of apertures 35c and 36care formed in offset positions relative to one another. Therefore, theseapertures 35c and 36c are linearly and vertically aligned when installedon the endless chain and link subassemblies 30. As also mentioned above,the lift rails 40 are secured to the inner links 35c and outer links 36cby means of fasteners 41 which extend through such aligned apertures 35cand 36c. As a result, the lift rails 40 (and the individual lift fingersubassemblies 45 mounted thereon) are all linearly and verticallyaligned with one another for use, as shown in in FIG. 3.

Referring back to FIG. 3, it can be seen that the illustrated endlesschain and link subassembly 30 extends about both the upper sprocket 22and the lower sprocket 24. As mentioned above, a plurality of pairs ofupper sprockets 22 and lower sprockets 24 are mounted along the lengthsof the upper shaft 21 and the lower shaft 23, respectively. For each ofthese pairs of upper and lower sprockets 22 and 24, an endless chain andlink subassembly 30 is carried thereon as shown in FIG. 3. Thus, whenthe upper shaft 21 is rotated by the motor 25, the cooperation of theendless chain and link subassemblies 30 with the upper and lowersprockets 22 and 24 causes corresponding rotation of the lower shaft 23.

Referring now to FIG. 8, the manner in which the endless chain and linksubassemblies 30 is supported on the accumulator 15 for movement isillustrated. As shown therein, first and second L-shaped brackets 47 and48, respectively, are provided for supporting and guiding the endlesschain and link subassembly 30 for movement. The first L-shaped bracket47 has a first leg portion which is secured to the frame 20 of theaccumulator 15 and a second leg portion which extends perpendicular tothe first leg portion. The second L-shaped bracket 48 has a first legportion which is secured to the first leg portion of the first L-shapedbracket 47 by means of threaded fasteners 49 and a second leg portionwhich extends perpendicular to the first leg portion.

The second leg portions of the first and second L-shaped brackets 47 and48 define a vertically extending channel, within which the roller chain31 of the endless chain and link subassembly 30 is supported and guidedfor movement. If desired, a conventional slot (not shown) or other meansmay be formed in one of the first or second L-shaped brackets 47 and 48to facilitate adjustment of the relative positions of the second legportions and, therefore, the size of the guide channel defined thereby.As discussed above, the inner and outer links 35 and 36 are carried onthe roller chain 31, while the lift rails 40 and the lift fingersubassemblies 45 are carried on the inner and outer links 35 and 36. Asimilar guide channel is provided on the back side of the accumulator15, and for each of the endless chain and link subassemblies 30.

Referring now to FIGS. 8 and 9, there is illustrated a means forconveying the cartons 17 from the intake end of the accumulator 15 tothe discharge end thereof. This means for conveying includes a pluralityof generally cylindrical rollers 50 which are disposed in alternatingfashion between the individual lift fingers 45b of the lift fingersubassemblies 45. The inner ends of the rollers 50 (i.e., the ends ofthe rollers 50 adjacent to the lift rails 40) are rotatably supported onrespective roller brackets 51 (see FIG. 3) which extends beneath theassociated roller 50. As best shown in FIG. 3, the roller bracket 51 issecured to a support bracket 52 which may be pivotably and resilientlymounted on the frame 20 of the accumulator 15. The outer ends of therollers 50 each have a pulley 50a secured thereto for rotationtherewith. The purpose of the pulleys 50a will be explained below.

Means are provided for rotatably driving the rollers 50 so as to advancecartons 17 from the intake end of the accumulator 15 to the dischargeend thereof (i.e., in the direction of the arrow in FIG. 9). In theillustrated embodiment, this means for rotatably driving includes adrive shaft 55 which is connected to a motor (not shown) so as to berotatably driven thereby. In the illustrated embodiment, this isaccomplished by a providing a pulley 56 which is mounted on the driveshaft 55 for rotation therewith. A drive belt 57 extends about thepulley 56 and the output shaft of the motor. Thus, when the motorrotates the output shaft, the drive belt 57 causes the drive shaft 55 torotate as well.

The drive shaft 55 extends axially along the length of the accumulator15, parallel to the flow of cartons 17 therethrough. A plurality ofendless elastomeric bands 58 are provided for connecting the drive shaft55 to each of the pulleys 50a. Each of the bands 58 extends about aportion of the drive shaft 55 and one of the pulleys 50a. Theelastomeric bands 56 are sized to frictionally engage both the driveshaft 55 and the individually pulleys 50a. Thus, when the drive shaft 55is rotated by the motor, the individual pulleys 50a (and the rollers 50connected thereto) are all rotated as well. As best shown in FIG. 9, theindividual lift fingers 45b of the lift finger subassemblies 45 arepositioned slightly below the vertical level of the rollers 50. As aresult, when the rollers 50 are rotatably driven, the cartons 17 can beadvanced freely through the accumulator 15 as shown.

Preferably, some of the rollers 50 are connected to their respectivepulleys 50a in a press fit relationship. This provides a secure drivingconnection therebetween which insures positive movement of the cartons17 in critical areas of the accumulator 15. However, others of therollers 50 are connected to their respective pulleys 50 in a slip fitrelationship. This slip fit relationship permits the cartons 17 toaccumulate within the conveyor section of the accumulator 15 withoutexcessive pressure being exerted thereon, which could possibly damagethe cartons 17.

The drive shaft 55 may be a single shaft extending throughout the axiallength of the accumulator 15, and the motor employed to rotate it may beeither a constant speed motor or a variable speed motor. Alternatively,as shown in FIG. 9, the drive shaft 55 may be divided into a pluralityof separate drive shaft sections, each of which is adapted to rotatablydrive a small group of the rollers 50. In this instance, some of thedrive shaft sections may be driven by constant speed motors, whileothers of the drive shaft sections may be driven by variable speedmotors. By providing both constant and variable speed motors, therollers 50 can be rotated at differing speeds to adjust the spacingbetween the adjacent cartons 17 within the accumulator 15. This may bedesirable when the accumulator 15 is operated to store or releasecartons 17, as will be described below.

As best shown in FIG. 9, one of the rollers 50 is not connected to thedrive shaft 55 by an elastomeric band 56. Rather, this roller 50 isconnected to a conventional blade stop assembly, indicated in dottedlines generally at 60. The blade stop assembly 60 includes a yoke 61 forrotatably supporting the roller 50 thereon, a stop plate 62 secured tothe upstream side of the yoke 61, and a vertically movable shaft 63. Theshaft 63 is connected to a conventional actuator (not shown), such as apneumatic actuator, for selective vertical movement. Thus, the actuatoris capable of selectively moving the stop plate 62 between a retractedposition (illustrated in solid lines) and an extended position(illustrated in dotted lines). When the blade stop assembly 60 is movedto the retracted position, the roller 50 is aligned with the otherrollers 50 of the accumulator 15. Thus, although the roller 50 mountedon the blade stop assembly 60 is not rotatably driven by any motor, itdoes permit cartons 17 to pass freely thereover when the other rollers50 are so driven. However, when the blade stop assembly 60 is moved tothe extended position, the stop plate 62 blocks the flow of cartons 17.Typically, a plurality of such blade stop assemblies 60 are providedwithin the accumulator 15, as will be described below.

Referring now to FIG. 10, there is schematically illustrated a controlcircuit, indicated generally at 70, for controlling the operation of theaccumulator 15. The control circuit 70 is conventional in the art andcan be embodied as a microprocessor or other computer. The controlcircuit 70 can interface with the operating equipment of the upstreamprocessing station 11, the conveyor system 12, and the downstreamprocessing station 13. To accomplish this, various sensors (not shown),including photoelectric devices and proximity sensors, may be providedto detect the locations and movements of cartons 17 at selected pointson the conveyor system 12 and within the accumulator 15 itself.Additional sensors (not shown) may be provided to monitor the positionof the lift rails 40 and other components of the accumulator 15. Thecontrol circuit 70 controls the operation of the various components inthe manner described below.

The operation of the accumulator 15 will now be described. Initially,the motor 25 of the accumulator 15 is energized so as to move theendless chain and link subassemblies 30 to an initial loading position,wherein the first shelf A1 is aligned slightly below the horizontallever of the rollers 50. This is accomplished by rotating the uppershaft 21 clockwise from the position illustrated in FIG. 3 until the A1shelf is properly aligned with the rollers 50. By first moving thecomponents of the accumulator 15 to this initial loading position, themaximum storage capacity of the accumulator 15 can be realized, as willbecome apparent below.

As discussed above, each of the first group of shelf positions A1through A15 is defined by a plurality of lift finger subassemblies 45having individual lift fingers 45b provided on both the upper and lowerend flanges thereof. In the initial loading position, the lowerindividual lift fingers 45b are positioned slightly below the verticallevel of the rollers 50, while the upper individual lift fingers 45b arepositioned well above the upper surfaces of the cartons 17. As a result,when the rollers 50 are rotatably driven, the cartons 17 can be advancedfreely through the accumulator 15 without engaging any of suchindividual lift fingers 45b, as described above.

During normal operation of the article handling system 10, the upstreamprocessing station 11 and the downstream processing station 13 bothfunction normally. Thus, the downstream processing station 13 is capableof handling all of the articles which are conveyed from the upstreamprocessing station 11. In this situation, the accumulator 15 merelyoperates to convey articles from the first conveyor 14 to the secondconveyor 16. To accomplish this, the drive shaft 55 is rotated by themotor as described above. As a result, the rollers 50 connected to thedrive shaft 55 are also rotated so as to advance the cartons 17 from theintake end of the accumulator 15 (adjacent to the first conveyor 14) tothe discharge end thereof (adjacent to the second conveyor 16). Also,all of the blade stop assemblies 60 are moved to the retracted positionsillustrated in FIG. 9 such that the stop plates 62 are not positioned toblock the movement of the cartons 17 across the rollers 50.

If the downstream processing station 13 subsequently becomes unable tocontinue accepting cartons 17 from the second conveyor 16, or if a jamoccurs in flow of cartons 17 through the second conveyor 16, the cartons17 will initially begin to back up on the second conveyor 16 downstreamof the accumulator 15. This backup of cartons 17 is sensed by one ormore of the sensors discussed above, and corresponding signals are sentto the control circuit 70. If the backup of cartons 17 is not clearedwithin a predetermined amount of time, the control circuit 70 can beoperated to place the accumulator 15 into an accumulation mode ofoperation to prevent the further flow of cartons 17 downstream of theaccumulator 15 until the problem is corrected.

In the accumulation mode of operation, the rotational speed of some ofthe rollers 50 is initially slowed relative to others of the rollers 50.This speed differential creates a gap of space between adjacent cartons17 moving through the conveyor section of the accumulator 15. Inresponse to a signal from a sensor (not shown) indicating that such gaphas been formed, the control circuit 70 can actuate a first blade stopassembly 60 to move from its retracted position to its extendedposition. This first blade stop assembly 60 is typically located nearthe discharge end of the accumulator 15. As a result, the associatedblade stop yoke 61 and stop plate 62 are moved upwardly into the gapbetween adjacent cartons 17 moving through the conveyor section of theaccumulator 15. Such movement blocks the flow of cartons 17 out of theaccumulator 15. Thus, cartons 17 which are located downstream of theextended blade stop assembly 60 will be conveyed out of the accumulator15, but cartons 17 which are located upstream will be blocked therein.

The cartons 17 located upstream of the extended blade stop assembly 60then begin to engage one another and back up within the conveyor sectionof the accumulator 15. The rollers 50 which are connected to theirassociated pulleys 50a in a slip fit relationship permit this to occurin a gentle fashion, as discussed above. Sensors located within theaccumulator 15 monitor this backup and generate signals to the controlcircuit 70. When the cartons 17 have backed up to the intake end of theaccumulator 15, the control circuit 70 actuates means (such as aconventional squeeze gate located immediately upstream of the intake endof the accumulator 15) for preventing the entry of additional cartons 17into the accumulator 15. The control circuit 70 also actuates a secondblade stop assembly between the first blade stop assembly and thedischarge end of the accumulator 15. The control circuit 70 lowers thefirst blade stop assembly. The group of cartons 17 which had been backedup to the intake end of the accumulator 15 are then conveyed into theaccumulator 15 until blocked by the second blade stop assembly. Uponconfirmation from appropriate sensors that no cartons 17 remain in theintake end of the accumulator 15, the accumulator 15 is ready toaccumulate the group of cartons 17 on the A1 shelf.

To accumulate a group of cartons 17 on the A1 shelf, the control circuit70 actuates the motor 25 to rotate the upper shaft 21 in thecounterclockwise direction when viewing FIG. 3. Thus, the uppersprockets 22 mounted on the upper shaft 21 are also rotated to causemovement of the associated endless chain and link subassemblies 30. Asdiscussed above, the endless chain and link subassemblies 30 carry thelift rails 40 and the lift finger subassemblies 45. Consequently, all ofthe shelf positions A1 through D33 are indexed counterclockwise from theinitial loading position to the next loading position, wherein the A2shelf is aligned with the rollers 50 of the conveyor section of theaccumulator 15.

When this occurs, the A1 shelf is elevated above the rollers 50. This isaccomplished as the lower row of the individual lift fingers 45b moveupwardly through the conveyor section, between the rollers 50 and theblade stop assemblies 60. Such movement of the individual lift fingers45b causes them to engage the bottom surfaces of the cartons 17 and liftthem upwardly off of the rollers 50. This upward movement continuesuntil the next shelf A2 is indexed into the next loading position,similar to the initial loading position previously occupied by the A1shelf. In this second loading position, the A2 shelf is prepared toaccept a second row of cartons 17 for accumulation. When the A2 shelfhas reached this next loading position, a conventional shelf positionsensor (not shown) generates a signal to the control circuit 70 to stopthe rotation of the upper shaft 21 by the motor 25. The shelf loadingprocess and indexing process described above is then repeated for eachof the shelf positions A2 through B28 as needed.

Preferably, the motor 25 which rotates the upper shaft 21 is a variablespeed motor. When the accumulator 15 is indexed from one loadingposition to another, the motor 25 can be energized to initiallyaccelerate to a relatively rapid speed, then decelerate as the indexmovement nears completion. Additional position sensors (not shown) maybe provided to sense the movement of the lift rails 40 during theindexing process so as to permit the motor 25 to be controlledaccordingly. Operation of the accumulator 15 in this manner minimizeswear on the indexing mechanism, permits faster and smoother operation,and provides for more gentle handling of the cartons 17 carried thereon.

As discussed above, all of the shelf positions in the first group A1through A15 are defined by lift rails 40 having lift fingersubassemblies 45 secured to both the upper and lower end flangesthereof. This is necessary because all of these first fifteen shelfpositions A1 through A15 will be indexed up the one front side of theaccumulator 15 (i.e., the right side when viewing FIG. 3), over theupper end, and down the back side thereof to fully fill the accumulator15, as shown in FIG. 3. Thus, on the back side of the accumulator 15,the upper lift finger subassemblies 45 now support the cartons 17,instead of the lower lift finger subassemblies 45 on the front sidethereof.

However, unlike the first group of shelf positions A1 through A15, noneof the shelf positions in the second group B16 through B28 can be movedover the upper end of the accumulator 15. To do so would cause the firstshelf A1 to be indexed so far downwardly along the back side of theaccumulator 15 that it would begin moving under the lower end thereof.As a result, the cartons 17 carried thereon would be dumped off the A1shelf. Thus, the shelf positions in the second group B16 through B28always remain on the front side of the accumulator 15. Therefore, thesecond group of shelf positions B16 through B28 are provided only withone lower set of lift finger subassemblies 45.

For the same reason, no cartons 17 can be loaded onto and raised by thethird group of shelf positions C29. However, as mentioned above, liftrails 40 are provided on the third group of shelf positions C29. Theselift rails 40 function merely as inner guide rails to support the innersides of the cartons which can be stored thereon in the conveyor sectionof the accumulator 15 (or merely conveyed therethrough), but not indexedupwardly. Thus, as discussed above, none of the lift rails 40 in thethird group of shelf positions C29 are provided with any of the liftfinger subassemblies. As also mentioned above, the fourth group of shelfpositions D30 through D33 are not provided with any lift rails 40 orlift finger subassemblies 45, since none of the cartons 17 can be storedthereon. Thus, it will be appreciated that although the illustratedaccumulator 15 defines a total of thirty-three shelf positions, onlytwenty-nine of such shelf positions can actually be used to storecartons 17 thereon.

FIG. 11 best illustrates how the endless chain and link subassemblies 30function as the various shelf positions are moved up the front side ofthe accumulator 15 and over the upper portion thereof. There are threezones of operation in the accumulator 15. The first zone of operation isthe vertical travel zone, which is illustrated by the outer link 36carrying the A11 shelf. The vertical travel zone encompasses those areasof the accumulator 15 where the links 35 and 36 are guided solely by thecooperation of the rollers 32 of the endless chain and link subassembly30 with the guide channels defined by the L-shaped brackets 47 and 48.This includes both links 35 and 36 which are moved vertically up thefront side of the accumulator 15 and down the back side thereof.

As shown in FIG. 11, the outer link 36 carrying the A11 shelf iseffectively supported on the lower three of the four elongated pins 33which extend therethrough (namely, the second, third, and fourth whencounting downwardly). As discussed above with reference to FIG. 6, theelongated pins 33 (which are carried on the rollers 32 disposed withinthe guide channel) extend through both the first pair of apertures 36band through the arcuate slots 36d. The outer edges of the first pair ofapertures 36b and the outer edges of the arcuate slots 36d are linearlyaligned, as shown by the dotted line 36f in FIG. 6. As a result,undesirable tipping or pivoting movement of the outer link 36 carryingthe All shelf (clockwise when viewing FIG. 11) under the weight exertedby the cartons 17 carried thereon is minimized because of the relativelylong distance separating the second elongated pin 33 (extending throughthe upper one of the first pair of apertures 36b ) from the fourthelongated pin 33 (extending through the lower one of the arcuate slots36d).

In a conventional roller chain assembly, the links would be connected toonly two adjacent elongated pins 33. This relatively short distance ofseparation would permit a much larger amount of this tipping or pivotingmovement in the vertical travel zone for a given amount of play betweenthe rollers 31 and the L-shaped brackets 47 and 48 of the guide channel.In the illustrated links, the distance of separation is much greater,resulting in much less ability for tipping or pivoting movement.

The second zone of operation is the transition zone, which isillustrated by the inner link 35 carrying the A10 shelf. The transitionzone encompasses those areas of the accumulator 15 where the links 35and 36 are located between the ends of the guide channels and theadjacent sprockets 22 and 24. Again, this includes links 35 and 36entering into and exiting from both the upper sprockets 22 and the lowersprockets 24 of the accumulator 15, on both the front and back sidesthereof.

As the inner link 35 carrying the A10 shelf is moved upwardly out of theguide channel defined by the first and second L-shaped brackets 47 and48, the roller chain 31 carrying the inner link 35 carrying the A10shelf meshes with the upper sprocket 22 at a point indicated by M. Atthat point M, the upper pin 33 of the inner link 35 carrying the A10shelf engages the edge of the upper sprocket 22. At the same time, thelower pin 33 of the inner link 35 carrying the A10 shelf is beginning toexit from the upper end of the guide channel defined by the first andsecond L-shaped brackets 47 and 48.

Further rotation of the upper sprocket 22 causes the inner link 35carrying the A10 shelf to move upwardly such that the lower pin 33thereof is moved out of the guide channel. As a result, the inner link35 carrying the A10 shelf is no longer supported by such guide channel.Because of the weight of the cartons 17 supported on the A10 shelf,there is a tendency for the lower end of the inner link 35 carrying theA10 shelf to tip or pivot inwardly toward the lower end of the uppersprocket 22, as indicated by the arrow P. This would be undesirable,inasmuch as such movement would cause the A10 shelf to angle downwardlyand possible dump the cartons 17.

The structure of the inner links 35 and the outer links 36 minimizesthis undesirable tipping or pivoting movement. As discussed above, thelower slot 35d formed on the inner link 35 carrying the A10 shelf ismounted on the same elongated pin 33 of the roller chain 31 as the upperslot 36d formed on adjacent outer link 36 carrying the A11 shelf. Theouter link 36 carrying the A11 shelf is, at this point, still guidedwithin the guide channel defined by the first and second L-shapedbrackets 47 and 48. Thus, the undesired movement of the inner link 35carrying the A10 shelf is minimized by the outer link 36 carrying theadjacent A11 shelf. Consequently, it can be seen that the uniquestructure of the inner links 35 and the outer links 36 minimizes thisundesired movement as such links 35 and 36 are transferred through thetransition zones.

The third zone of operation is the rotary travel zone, which isillustrated by the outer link 36 carrying the A9 shelf. The rotarytravel zone encompasses those areas of the accumulator 15 where thelinks 35 and 36 are guided solely by the cooperation of the rollers 32of the endless chain and link subassembly 30 with the upper and lowersprockets 22 and 24. This includes both links 35 and 36 which are movedover the upper portion of the accumulator 15 and under the lower portionthereof.

As shown in FIG. 11, the outer link 36 carrying the A9 shelf iseffectively supported on all four of the elongated pins 33 which extendtherethrough. As discussed above with reference to FIG. 6, the elongatedpins 33 (which are carried on the rollers 32 disposed within the guidechannel) extend through both the first pair of apertures 36b and throughthe arcuate slots 36d. The inner edges of the first pair of apertures36b and the inner edges of the arcuate slots 36d are aligned along anarc defined by a radius R, as shown by the dotted line 36g in FIG. 6.This radius R is equal to the radius of each of the upper and lowersprockets 22 and 24, as shown in FIG. 11. Thus, undesirable tipping orpivoting movement of the outer link 36 carrying the A9 shelf when thecartons 17 are moved over the upper portion of the accumulator 15 isminimized because the links 35 and 36 are fully supported on thesprockets 22 and 24.

The accumulator 15 will continue to accumulate cartons 17 on the shelfpositions A1 through C29 until sensors (not shown) on the secondconveyor 15 indicate that the backup has been cleared, or until all ofsuch shelf positions A1 through C29 are filled with cartons 17. When thebackup has been cleared, the control circuit 70 can be operated to placethe accumulator 15 into a de-accumulation mode of operation to re-startthe flow of cartons 17 downstream of the accumulator 15. Thede-accumulation mode of operation is essentially the reverse of theaccumulation mode described above, with each of the shelf positions C29through A1 being sequentially lowered when appropriate such that thecartons 17 are placed onto the rollers 50. The rollers 50 then conveythe cartons 17 out of the accumulator 15 so that the next shelf can belowered.

As discussed above, the illustrated accumulator 15 is provided withthirty-three shelf positions, each being provided with lift rails 40 andlift finger subassemblies 45 capable of storing one row of cartons 17thereon. This invention contemplates each of the shelf positions can, ifdesired, be capable of storing two or more rows of cartons thereon. Thiscan be accomplished by modifying the structures of the lift rails 40 andthe lift finger subassemblies 45 such that each shelf position issub-divided by two or more rows of individual lift fingers 45b. Suchsub-divided rows can be filled in the same manner as described above,except that the motor 25 would be operated to index the endless chainand link subassemblies 30 only partially between adjacent shelfpositions. The sub-divided rows of individual lift fingers 45b wouldmove as a unit, inasmuch as they would all be carried upon a single oneof the inner and outer links 35 and 36.

In accordance with the provisions of the patent statutes, the principleand mode of operation of this invention have been explained andillustrated in its preferred embodiment. However, it must be understoodthat this invention may be practiced otherwise than as specificallyexplained and illustrated without departing from its spirit or scope.

What is claimed is:
 1. An accumulator for movably supporting an articlecomprising:a frame; a wheel rotatably supported upon said frame, saidwheel defining a radius; means for selectively rotating said wheel; amember engaged with said wheel for movement when said wheel is rotated;a link carried on said member for movement therewith, said link havingat least one aperture formed therethrough and at least one slot formedtherethrough, said aperture and said slot having first edges whichdefine a straight line and having second edges which define a radiuswhich is substantially equal to said radius defined by said wheel; andmeans secured to said link for supporting an article thereon formovement with said link and said member when said wheel is rotated. 2.The accumulator defined in claim 1 wherein said wheel is a sprocket andsaid member is a chain engaged with said sprocket.
 3. The accumulatordefined in claim 1 wherein said wheel is a first wheel, and furtherincluding a second wheel rotatably supported upon said frame, saidmember being engaged with both said first wheel and said second wheel.4. The accumulator defined in claim 3 wherein said second wheel definesa radius which is equal to said radius defined by said first wheel. 5.The accumulator defined in claim 1 wherein said member is formed as anendless loop.
 6. The accumulator defined in claim 1 further includingfirst and second pins supported on said member, said first pin extendingthrough said aperture of said link and said second pin extending throughsaid slot of said link.
 7. The accumulator defined in claim 1 whereinsaid link further includes a second aperture, said first and secondapertures and said slot having first edges which define a straight lineand having second edges which define a radius which is substantiallyequal to said radius defined by said wheel.
 8. The accumulator definedin claim 7 further including first, second, and third pins supported onsaid member, said first pin extending through said first aperture ofsaid link, said second pin extending through said second aperture ofsaid link, and said third pin extending through said slot of said link.9. The accumulator defined in claim 1 wherein said link further includesa second slot formed therethrough, said aperture and said first andsecond slots having first edges which define a straight line and havingsecond edges which define a radius which is substantially equal to saidradius defined by said wheel.
 10. The accumulator defined in claim 9further including first, second, and third pins supported on saidmember, said first pin extending through said aperture of said link,said second pin extending through said first slot of said link, and saidthird pin extending through said second slot of said link.
 11. Theaccumulator defined in claim 1 wherein said link further includes asecond aperture and a second slot formed therethrough, said first andsecond apertures and said first and second slots having first edgeswhich define a straight line and having second edges which define aradius which is substantially equal to said radius defined by saidwheel.
 12. The accumulator defined in claim 11 further including first,second, third, and fourth pins supported on said member, said first pinextending through said first aperture of said link, said second pinextending through said second aperture of said link, said third pinextending through said first slot of said link, and said fourth pinextending through said second slot of said link.
 13. The accumulatordefined in claim 1 further including a plurality of links carried onsaid member for movement therewith, each of said links having at leastone aperture formed therethrough and at least one slot formedtherethrough, said aperture and said slot of each of said links havingfirst edges which define a straight line and having second edges whichdefine a radius which is substantially equal to said radius defined bysaid wheel.
 14. The accumulator defined in claim 1 wherein said meanssecured to said link for supporting an article includes a lift fingermounted on said link.
 15. The accumulator defined in claim 14 whereinsaid lift finger extends at an angle relative to a plane extendingperpendicular to a plane defined by said link.
 16. The accumulatordefined in claim 1 wherein said means secured to said link forsupporting an article includes a pair of lift fingers mounted onopposite ends of said link.
 17. The accumulator defined in claim 16wherein each of said lift fingers extends at an angle relative to aplane extending perpendicular to a plane defined by said link.
 18. Theaccumulator defined in claim 17 wherein said lift fingers extendinwardly toward one another.